The present invention relates generally to semiconductor fabrication and, more particularly, a linear chemical mechanical planarization (CMP) system and method for planarizing a wafer.
In the fabrication of semiconductor devices, CMP is used to planarize globally the surface of an entire semiconductor wafer. CMP has three key parameters that need to be optimized, namely (1) defects, (2) dishing, and (3) throughput. During the fabrication of semiconductor devices, a number of CMP operations are typically carried out (e.g., bulk copper removal, barrier removal, buffing, over polish, etc.), and each CMP operation has a unique process condition. To optimize each of the three key CMP parameters, a single CMP system typically includes several CMP modules with each module uniquely optimized for each CMP operation.
FIG. 1 is a simplified schematic diagram of a conventional CMP system 100 that includes three linear CMP modules. As shown in FIG. 1, CMP system 100 includes a first linear CMP module (LPM1) 102, a second linear CMP module (LPM2) 104, and a third linear CMP module (LPM3) 106. In one configuration, LPM1 102 and LPM2 104 have polyurethane belt pads configured for bulk copper removal. On the other hand, LPM3 106 has a Politex belt pad configured for barrier removal and buffing. Although defects and throughput are optimized in this configuration, topography is compromised. In another configuration, LPM1 102, LPM2 104, and LPM3 106 all have polyurethane belt pads configured for bulk copper removal, barrier removal, and buffing, respectively. Although topography and throughput are optimized in this configuration, defects are compromised. In still another configuration, LPM1 102 and LPM2 104 have polyurethane belt pads configured for bulk copper removal and barrier removal, respectively. LPM3 106 has a Politex belt pad configured for buffing. Although topography and defects are optimized in this configuration, throughput is compromised.
In view of the foregoing, there is a need for a linear CMP system that can optimize all three key CMP parameters.